Lubricating stuffing box



May 5, 1925.

, 1,536,378 F. s. CRAVEN LUBRIGATING STUFFING BOX Filed Aug. 17, 1920 raven fiazwzs' 6 INVENTOR. Wmvess "A TTORFVEY;

Patented May 5, 1925.

UNITED STATES PATENT OFFICE.

FRANCIS SJ CRAVEN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIG-NOR TO- THE GOVERNMENT OF THE UNITED STATES.

LUBRIGATING STUFFINGCBOX.

Application filed August 17, 1920. Serial No. 404,277.

To. all whom it may concern:

Be it known that I, FRANCIS .S. C AVEN, a

citizen of the United States, residing at Washington, District of Columbia, have invented new andluseful Improvements in Lubricating Stuffing Boxes, of which the following isa specification.

This invention relates to improvements in grease cups or stuffing boxes particularly adapted for use on visual instruments on board ship for fire control and other puroses.

One of the objects of the present invention is to provide a simple and practical stuffing box of the above character, which may be inexpensively manufactured, assembled, and installed.

A. further object is to provide a stutfing box of the above character which will be entirely air and moisture proof as well as frictionless in use and operation.

A further object is to provide an improved stuffing box in which a shaft extending from the interior to the exterior of a casing will be most efliciently lubricated. at its point of passage and at the same time will completely prevent passage of air to and from the interior of the casing.

With these and other objects in mind which will appear obvious from the following description when taken in connection with the accompanying sheet of drawings forming part of this disclosure, attention is directed to the single view illustrating in cross section a part of the casing and shaft passing therethrough together with the grease cup.

In order that a clearer conception of the present invention may be had, it should be stated that wherever shaftings pierce the wall or cover of an instrument such as a fire control visual instrument these shaftings are fitted with water-tight glands.

' In instruments of the above general character, which frequently include a motor, there results in operation a gradual rise of internal temperature causing 2. corresponding rise in the internal pressure of the air contents. The increased internal pressure results in air leakage from within to. the external air through openings which are entirely too small of themselves to permit the passage of liquid or to facilitate the circulation of air at normal atmospheric pressure. Upon turning olf the motor the interior .of the instrument cools with the result of" a correspondingwloss of interior pressure. so that a reverse flow of air results. This atmospheric air carries with it a' pre vailing quantity of suspended moisturewhich begins to condense on cooling of the instrument. As this process is repeated, larger quantities of suspended moisture accumulate within the casing until a degree of saturation occurs resulting in condensation producing the effect known as sweating. This, of course, is exceedingly objectionable to delicate instruments of the character referred to but by the use of the grease packing stuiiing box herein shown and described this, among other objections is eliminated resulting in a more efficient and reliable instrument as a whole.

Referring now to the figure a shaft 1 passes through a wall 2 of the casing which is provided with an enlarged pocket or recess 3 surrounding a reduced portion 4 of the shaft. This pocket communicate through a passage 5 with an oil or grease cup 6 of any desired type threaded at 7 to engage a tapped recess in the exterior wall of the casing. The interior of the wall of the casing is illustrated with a conical recess adapted to receive a conical bushing 8 held in place by means of screws 10, although it is obvious that the form of this bushing may be varied, or it may be omitted, without lessening the value of the grease packing. It will also be noted that the casing is provided with a leak-off groove 11 as indicated by the dotted lines. This leak-off permits the manipulator of the grease cup 6 to see when he has completely filled the pocket- 3 with grease. It also insures lubrication of the shaft 1 at that point and opposes a flow of grease against the direction of air tending to enter through the gland.

The purpose of the small reduction in diameter of the shaft as indicated at 4 within the gland is to remove the cleavage surface of the grease from the direct line by which moisture or air can reach the gland thus preventing seepage between the grease and the shafting.

It is believed that from. the above description the invention will be thoroughly understood to those skilled in the art.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can by applying current knowledge readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, and, therefore, such adaptations should and are int-ended to be comprehended within the meaning and range of equivalency of the following claims.

What I claim is 1. A stutfing box of the above character comprising a casing wall having a recessed part, a shaft passing therethrough having a recessed part coincident with the first mentioned part thereby to form a chamber, means for conducting a lubricant to said chamber, and removable means closing one end of said chamber, said wall of the casing being provided with a leak-off groove extending along the shaft on the exterior side of the wall to indicate visually that the chamber is filled with lubricant.

2. In combination, a casing having an en larged central opening, a shaft passing through a wall of said casing and provided with a reduced portion coincident with said central opening thereby to form a chamber adapted to receive a lubricant and air tight means adapted to force said lubricant into said chamber, one side of said chamber being closed by a removable closure, said wall being provided with a leak-0d groove between said chamber and the exterior of said casing for indicating visually when said chamber is filled with lubricant.

Signed at Washington, District of Columbia, this 20th day of April, 1920.

F. S. CRAVEN. 

